Intensities, broadening and narrowing parameters in the ν3 band of methane

•Absolute line intensities of 9 lines in the P branch of the CH4ν3 band are measured accurately.•Broadening coefficients with 7 perturbers for 9 lines in the P branch of the CH4ν3 band are measured accurately.•Narrowing parameters with 4 perturbers for 7 lines in the P branch of the CH4ν3 band are measured accurately.•Spectroscopic parameters are measured using a narrow emission line width difference-frequency-generation infrared spectroscopy.•Spectroscopic parameters are deduced using Voigt and Galatry profiles.

The P-branch of methane׳s ν3 band is probed to carry out an extensive study of the 2905-2908 cm−1 infrared spectral region. Absolute line intensities as well as N2-, O2-, H2-, He-, Ar- and CO2-broadening coefficients are determined for nine transitions at room temperature. Narrowing parameters due to the Dicke effect have also been investigated. A narrow emission line-width (~0.0001 cm−1) difference-frequency-generation (DFG) laser system is used as the tunable light source. To retrieve the CH4 spectroscopic parameters, Voigt and Galatry profiles were used to simulate the measured line shape of the individual transitions.